1. Field of the Invention
The present invention relates to a sensor attachment device, a sensor and a light emitting device for a photo-electrical sensor, and in particular, to an improvement of an attachment arrangement of a sensor main body and a light emitting device main body.
2. Description of the Related Art
One known method of fixing a sensor such as a photo-electrical sensor is to prepare a threaded sensor main body, attach a nut that is threaded so as to correspond to the thread of the sensor main body, and rotate the nut thereby attaching the sensor main body to a holding member that has been previously fixed to an installation position (refer to, e.g., Japanese Unexamined Utility Model Application Publication No. H7-36339).
FIG. 16 is a perspective view of one example of an attachment arrangement of a sensor main body 102 in a conventional sensor 101. In this example, an almost L-shaped holding member 103 is previously fixed at an installation position for the sensor 101, and the sensor main body 102 is attached to the holding member 103 by means of a nut 104. A portion of the sensor main body 102 forms an insertion portion 105 that is to be inserted into an opening (not shown) in the holding member 103, and a thread (not shown) is formed along an external surface around the insertion portion 105.
In attachment of the sensor main body 102 to the holding member 103, after inserting the insertion portion 105 of the sensor main body 102 into the opening of the holding member 103, the nut 104 that is threaded so as to correspond to the thread of the insertion portion 105 is screwed onto the insertion portion 105 from its tip. Then, the nut 104 is rotated and fastened so as to hold the holding member 103 between the nut 104 and the sensor main body 102, thereby firm attachment of the sensor main body 102 to the holding member 103 being established. In order to make holding and rotating of the nut 104 easier, a concavo-convex portion 106 is provided over an external surface of the nut 104.
However, the above described conventional attachment arrangement of the sensor main body 102 is cumbersome, because it requires inserting the insertion portion 105 of the sensor main body 102 into the opening of the holding member 103, screwing the nut 104 onto the insertion portion 105, and then rotating and fastening the nut 104. In particular, it becomes significantly cumbersome in such a case where a production line is provided with a number of sensors 101, because the above operations have to be repeated for each of the sensors 101.
Further, in a configuration in which the sensor main body 102 is attached to the holding member 103 by fastening the nut 104 as described above, the sensor main body 102 can adversely rotate to an angle that exceeds a desired angle due to a fastening torque occurring when fastening the nut 104. In this case, if the sensor is a photo-electrical sensor provided with a light emitting element and a photo-electrical element, for example, possible misalignment in a floodlight axis or a light-receiving axis prevents the sensor from performing favorable detection. Moreover, in a case in which the nut 104 is manually held and screwed, adjustment of the fastening torque becomes difficult and the sensor main body 102 can adversely jounce due to the lack of the fastening torque.